1. the journal could work like the codex umbra, with a crafting tab for summoning creatures. Might include:
-gnomes
-archibald corduroy
-wax figures (of different assortments)
-lilliputians
-etc.
2. if any other gravity falls characters are released, maybe they can have different journals, each one doing something diffent.
3. Mabel and Grunkle Stan. If you decide to make mods for them, here are a few ideas.
4. Mabel:
Health: low
Hunger: high
Sanity: mid
-can craft smile dip, which makes recipient hyper
-has a grappling hook
-crafts sweaters with different effects
-has waddles, + a sanity aura
5. Stan
Health: mid
Hunger: mid
Sanity: high
-has tier 1 and 2 science already
-can craft portals
-hunger drains fast
Any other suggestions can be commented below.